JP2532696B2 - Working fluid - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a working fluid used for a heat pump device such as an air conditioner and a refrigerator.

2. Description of the Related Art Conventionally, in heat pump devices such as air conditioners and refrigerators, fluorocarbons (hereinafter referred to as ROO or ROO) are used as a working fluid.
Halogenated hydrocarbons referred to as ○) are known, and are usually used when the condensing temperature and / or the evaporating temperature are in the range of about 0 to about 50 ° C. Among them, chlorodifluoromethane (CHClF ₂ , R22) is widely used as a working fluid for home air conditioners, building air conditioners, large refrigerators and the like.

Problems to be Solved by the Invention However, in recent years, the depletion of the stratospheric ozone layer by CFCs has become a global environmental problem, and the CFCs that have a large ozone depletion ability in the stratosphere (hereinafter referred to as “specific CFCs”) have already been The treaty regulates the amount used and the amount produced, and there is a movement to abolish the use and production of specified CFCs in the future. By the way, R22 has a very small ozone depletion coefficient (stratospheric ozone depletion capacity when tolylochlorofluoromethane (CCl ₃ F) has a stratospheric ozone depletion capacity of 1; hereinafter referred to as ODP), which is as small as 0.05, and is not a specific CFC. It is expected that the amount of use will increase in the future, and now that the refrigeration and air-conditioning equipment has become widespread, the increase in the amount of use and production of R22 will have a great impact on the human living environment. Therefore, although the stratospheric ozone depletion capacity is small, it is said that it has some destructive capacity.
There is also a strong demand for early development of working fluids that can replace the above.

The present invention has been made in view of the above-described problems, and provides a working fluid that has almost no influence on the stratospheric ozone layer and is an alternative to R22.

Means for Solving the Problems In order to solve the above problems, the present invention provides at least difluoromethane (CH ₂ F ₂ ) and tetrafluoroethane (C ₂ H _2
2 F ₂ ) and difluoroethane (C ₂ H ₄ F ₂ ) including three types of CFCs, difluoromethane approximately 20 to approximately 60% by weight, tetrafluoroethane 0 to approximately 80% by weight, difluoroethane 0 to approximately
It is characterized in that the composition range is 65% by weight, and in particular, about 25 to about 50% by weight of difluoromethane, 0 to about 75% by weight of tetrafluoroethane, and 0 to about 50% of difluoroethane.
A composition range of approximately 65% by weight is desirable.

Action The present invention uses the above-mentioned combination to convert the working fluid into difluoromethane (ODP = 0), tetrafluoroethane (ODP = 0), and fluorocarbons having almost no ozone depletion ability, which are fluorocarbons having no chlorine in the molecular structure. By using a mixture of difluoroethane (ODP = 0), the effect on the stratospheric ozone layer is smaller than that of R22 and can be almost eliminated. In addition, the present invention has a vapor pressure similar to that of R22 at about 0 to about 50 ° C., which is the use temperature of a heat pump device such as an air conditioner or a refrigerator, by setting the above composition range, and the present invention is used as a substitute for R22. It is possible to provide a working fluid usable in the device. Therefore, in the above combinations and composition ranges
ODP is also expected to be 0, and it is a very promising working fluid as an alternative to R22. In addition, since such a mixture becomes a non-azeotropic mixture and has a temperature gradient in the condensation process and the evaporation process, a coefficient of performance higher than that of R22 can be expected by configuring a Lorentz cycle with a temperature difference close to that of the heat source fluid. It is.

In general, fluorocarbons capable of depleting stratospheric ozone tend to have a greater effect of global warming as the ODP value increases, but the working fluid according to the present invention has an ODP of 0.
It is estimated that the effect of global warming is the same as R22 or less than R22 because it is composed of a mixture of three or more fluorocarbons. It is also possible to make it small.

Embodiment An embodiment of a working fluid according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a constant flow of a working fluid composed of a mixture of three fluorocarbons of difluoromethane (R32), 1,1,1,2-tetrafluoroethane (R134a) and 1,1-difluoroethane (R152a). The equilibrium state at temperature and constant pressure is shown using triangular coordinates. In the triangular coordinates, a single substance is arranged at each vertex of the triangle in the order of lower boiling point in a counterclockwise direction from the upper vertex as a base point, and the composition ratio (weight ratio) of each component at a certain point on the coordinate plane Is represented by the ratio of the distance between the point and each side of the triangle. In addition, at this time, the distance between the point and the side of the triangle corresponds to the composition ratio of the substance described at the apex of the triangular coordinate in the pattern facing the side. In FIG. 1, 1 is a gas-liquid equilibrium line of the mixture at a temperature of 0 ° C. and a pressure of 4.044 kg / cm ² G, which corresponds to the saturated state of R22. Vapor-liquid equilibrium line (R22 equivalent to 0 ° C) 1
The upper line represents the saturated gas phase line, the lower line represents the gas-liquid equilibrium line (corresponding to R220 of 0 ° C), and the lower line represents the saturated liquid phase line. . 2 is
This is the vapor-liquid equilibrium line for the mixture at a temperature of 50 ° C and a pressure of 18.782 kg / cm ² G, and this temperature and pressure also correspond to the saturated state of R22. The composition on the saturated vapor line vaporizes at a pressure higher than R22 and liquefies at the same pressure as R22. The composition on the saturated liquidus line vaporizes at the same pressure as R22 and liquefies at a pressure lower than R22. The composition in the area between these two lines is R2
It vaporizes at a pressure higher than 2 and liquefies at a pressure lower than R22.
That is, the composition in the area between the vapor-liquid equilibrium line 2 at 50 ° C changes from the gas phase to the liquid phase at a pressure lower than R22 at 50 ° C, and the gas phase higher than 50 ° C condenses at the same pressure as R22. Then, the liquid phase changes to a temperature lower than 50 ° C. Moreover, the composition in the area between the vapor-liquid equilibrium line 1 at 0 ° C. is R22 at 0 ° C.
At a higher pressure, the liquid phase changes to a gas phase, and at the same pressure as R22, a liquid phase lower than 0 ° C evaporates and changes to a gas phase higher than 0 ° C. As you can see, R32, R134a and R152a
Are about 20 to about 60% by weight, 0 to about 80% by weight, 0 to about
The composition range of 65% by weight is desirable because it has a vapor pressure almost equal to that of R22 at a use temperature of about 0 to about 50 ° C. Further, R32, R134a and R152a are each approximately 25 ~
The composition range of about 50% by weight, 0 to about 75% by weight, and 0 to about 65% by weight has a vapor pressure almost equal to that of R22 at all use temperatures between 0 ° C and 50 ° C. desirable.

The composition of the working fluid at points A ₁ to F ₁ in FIG.
Shown in the table. Points A ₁ ~ point C ₁ is a gas-liquid equilibrium line (R22 50 ° C. equivalent)
It is on the saturated vapor phase line of No. 2 and the vapor-liquid equilibrium line (R220
The temperature is 0 ° C and the pressure is 4.044 kg / cm ² G because it is in the range sandwiched by both the saturated vapor phase line of 1) and the vapor-liquid equilibrium line of R22 (0 ° C) 1 At (corresponding to the saturated state of R22), there is a vapor-liquid equilibrium state. Also, point D ₁ to point F ₁
Is on the saturated liquidus line of gas-liquid equilibrium line (R22 0 ° C equivalent) 1, and the saturated vapor phase line of gas-liquid equilibrium line (R22 50 ° C equivalent) 2 and gas-liquid equilibrium line (R22 50 ° C equivalent) 2 Since it is in the range sandwiched by both saturated liquidus lines, the temperature is 5 At 0 ° C and a pressure of 18.782 kg / cm ² G (equivalent to the saturated state of R22), a gas-liquid equilibrium state is reached. Therefore, the working fluid having the composition shown in Table 1 achieves a saturated state or a gas-liquid equilibrium state under the condition of the saturated vapor pressure of R22 at 0 ° C. and 50 ° C. By operating at the saturated vapor pressure of R22 at the same temperature, it is possible to obtain a condensing temperature and an evaporation temperature substantially equal to R22.

Here, only the points on the gas-liquid equilibrium line (corresponding to R22 of 0 ° C.) 1 or the gas-liquid equilibrium line (corresponding to R22 of 50 ° C.) 2 have been described, but points inside the points A ₁ to F ₁ , that is, Temperature 0 ℃, pressure 4.044kg / cm ² G and temperature 50 ℃, pressure 18.872kg / c
By operating in the same manner for a working fluid having a composition in a gas-liquid equilibrium state at m ² G (both corresponding to the saturated state of R22), R22 at a use temperature of approximately 0 to approximately 50 ° C.
It is possible to obtain a condensing temperature and an evaporating temperature substantially equal to the above.

Figure 2 shows R32,1,1,1,2-tetrafluoroethane (R1
34), the equilibrium state at constant temperature and constant pressure of the working fluid composed of the mixture of three types of R152a R152a is shown by using triangular coordinates. In this triangular coordinate, the standard boiling point at atmospheric pressure is lower in R152a than in R134, but in relation to Fig. 1, at each vertex of the triangle, R32, R13 counterclockwise with the upper vertex as the base point.
4, Single substance is arranged in order of R152a. In Fig. 2, 3 is a vapor-liquid equilibrium line of the mixture at a temperature of 0 ° C and a pressure of 4.044 kg / cm ² G, and 4 is a temperature of 50 ° C and a pressure of 18.782 kg.
² is a vapor-liquid equilibrium line of the mixture at / cm ² G. In this case, R32, R134 and R15a are each approximately 30 to approximately 60% by weight,
A composition range of 0 to about 70% by weight and 0 to about 65% by weight is desirable because it has a vapor pressure almost equal to that of R22.
2, R134 and R15a are each about 35 to about 50% by weight, 0 to about 6
A composition range of 5% by weight to 0 to about 65% by weight is particularly desirable.

The composition of the working fluid at points A ₂ to F ₂ in FIG.
Shown in the table. Points A ₂ to C ₂ are gas-liquid equilibrium lines (equivalent to R22 50 ° C)
On the saturated vapor phase line of 4, points D ₂ to E ₂ are gas-liquid equilibrium lines (R22 5
It is on the saturated vapor phase line of 0 ° C) 4 and both are vapor-liquid equilibrium lines (R
Saturated vapor phase line and vapor-liquid equilibrium line (R22
(Equivalent to 0 ° C), it is in the range between the two saturated liquidus lines, so that at a temperature of 0 ° C and a pressure of 4.044 kg / cm ² G (corresponding to the saturated state of R22), a vapor-liquid equilibrium state is established. . Also, point F ₂
Is on the saturated liquidus line of gas-liquid equilibrium line (R22 0 ° C equivalent) 3 and saturated gas phase line of gas-liquid equilibrium line (R22 50 ° C equivalent) 4 and gas-liquid equilibrium line (R22 50 ° C equivalent) 4 Since it is in the range between both saturated liquidus lines, the temperature is 50 ° C and the pressure is 1
At 8.782 kg / cm ² G (equivalent to the saturated state of R22), a gas-liquid equilibrium state is reached. Therefore, the working fluid having the composition shown in Table 2 was saturated or vaporized under the condition of the saturated vapor pressure of R22 at 0.50 ° C. By achieving a liquid equilibrium state and operating at a saturated vapor pressure of R22 at a use temperature of approximately 0 to approximately 50 ° C, it is possible to obtain almost the condensation temperature and evaporation temperature of R22. .

Here, only the points on the gas-liquid equilibrium line (corresponding to R22 0 ° C.) 3 or the gas-liquid equilibrium line (R22 50 ° C.) 4 are explained, but the points inside the points A ₂ to F ₂ , that is, Temperature 0 ℃ ・ Pressure 4.044kg / cm ² G and Temperature 50 ℃ ・ Pressure 18.782kg / c
By operating in the same manner for a working fluid having a composition in a gas-liquid equilibrium state at m ² G (both corresponding to the saturated state of R22), R22 at a use temperature of approximately 0 to approximately 50 ° C.
It is possible to obtain a condensing temperature and an evaporating temperature substantially equal to the above.

In the above examples, the working fluid is composed of a mixture of three types of freons, but it is of course possible to form the working fluid by a mixture of four or more types of freon including structural isomers. , Difluoromethane abbreviation
The composition range of 20 to about 60% by weight, tetrafluoroethane 0 to about 80% by weight, and difluoroethane 0 to about 65% by weight has a vapor pressure almost equal to that of R22 at a use temperature of about 0 to about 50 ° C. Desirable to have. Furthermore, difluoromethane approximately 25 to approximately 50% by weight, tetrafluoroethane 0 to approximately
A composition range of 78% by weight and 0 to about 65% by weight of difluoroethane is particularly desirable because it has a vapor pressure almost equal to that of R22 at all use temperatures between 0 ° C and 50 ° C. In particular, the ODP in the above combination and composition range is also 0.
It is expected to be a very promising working fluid as a substitute for R22. In addition, since such a mixture becomes a non-azeotropic mixture and has a temperature gradient in the condensation temperature and the evaporation process, a coefficient of performance higher than that of R22 can be expected by constructing a Lorentz cycle in which the temperature difference with the heat source fluid is close. Is.

EFFECTS OF THE INVENTION As is clear from the above description, the present invention provides a working fluid as a mixture of three or more kinds of only CFCs containing no chlorine in the molecular structure, and by specifying the composition range thereof, 1) The influence on the stratospheric ozone layer is smaller than that of R22, and it is possible to expand the range of selection of working fluid that makes it almost nonexistent. (2) It has the same vapor pressure as R22 at the operating temperature of the equipment. However, it can be used as an alternative to R22 in current equipment. (3) Utilizing the property of the temperature gradient of non-azeotropic mixture, R22
It has the effect that a higher coefficient of performance can be expected.

[Brief description of drawings]

FIG. 1 and FIG. 2 are diagrams showing the equilibrium state of a working fluid composed of a mixture of three types of fluorocarbons at a constant temperature and a constant pressure using triangular coordinates. 1,3 …… Gas-liquid equilibrium line (R22 0 ° C equivalent) 2,4 ……
Vapor-liquid equilibrium line (R22 equivalent to 50 ° C).

Claims (1)

(57) [Claims] 1. A fluorocarbon comprising three types of fluorocarbons of difluoromethane, tetrafluoroethane and 1,1-difluoroethane, wherein the difluoromethane is 20 to 60% by weight, the tetrafluoroethane is 80% by weight or less, and the 1,1- A working fluid containing 65% by weight or less of difluoroethane.